A schedule of values is a breakdown of a contract price into lines, each with a dollar value, agreed before work starts and used to figure progress payments.
On a paving job the lines usually follow the work: mobilization and traffic control, milling and transport, base repair, binder course, surface course, striping and signage, and closeout. The lines add up to the contract price. Each month you report the percent complete on each line, and the pay app bills the value completed to date, minus what you've already billed, minus retainage.
On commercial jobs that use AIA pay apps, the schedule of values is laid out on the G703 continuation sheet, which backs up the G702 application for payment.
Put real costs on the early lines like mobilization so you aren't financing the project. Front-loading is different. Inflating early lines to get paid ahead of the work, or claiming a line is further along than it is, gets every later pay app picked apart.
In Pavr the schedule of values is built from the signed proposal, and each pay app bills the percent complete on each line with retainage held until the release.